You could try this :
I started with your first image, which I realise is lower res than the second but it was the adjustments that matter. I added three adjustment layers.
The first darkens the cities and has a mask on the starts - the globe edge and the three cities
The second Hue/Sat turns most of the lights into a redder colour. It has a blend if so that it does not redden the blueish background glow
The third (curve ) brings up that dark blue glow (it has the same mask as the darken cities curve)
I hope that helps you
I added a hue saturation layer and dimmed down the brightness of the lights. On the layer of blue I copied earlier, I took the opacity down so it didn't jump off the image. I removed the holes in the previous masks that I used to let the lights shine through and instead, I used a star brush at 17% opacity and a medium yellow color and hit it about 10 times over each city, then a few more over the larger cities. I then created a merged layer and using unsharp mask, I sharpened the image to get a glow back to the white lights. There were two areas of white lights that were still too bright, so I used the clone brush to copy areas that fixed blended better. And this is the result. I sent it to the client and he was happy. Thanks for the advice! These forums are such a help!
Glad you got it sorted and the best part ...your client is happy.